Abstract
Operating superheater tubes of biomass-fired boilers at considerably higher temperatures than can be tolerated by commonly used structural materials could improve boiler efficiency. However, corrosion of the superheater tubes promoted by interaction with the relatively low melting point deposits that accumulate on the tubes becomes a major issue. The objective of this study was to use field exposures to determine if there are materials acceptable for use as superheater tubes that can operate at temperatures at least 100 Celsius degrees above the current maximum superheater temperature. Corrosion probes containing multiple specimens of nine different alloys were exposed for at least 2000 h in the superheater area of three biomass boilers where the deposits were determined to be enriched in potassium or chlorine. Similar specimens were also exposed in a boiler co-firing coal and wood. For the probes, specimen temperatures ranged from a low of less than 400°C to temperatures above 600°C for all but one case. Following exposure, a section was taken from each specimen and examined using light microscopy and scanning electron microscopy. Results of the examination of these specimens showed some alloys performed considerably better than others, but the corrosion resistance could not be related to chromium or molybdenum content of the alloys. Application: The results of this study provide guidance on the selection of superheater tube alloys for applications where it is desired to operate in hostile environment at temperatures as much as 100 Celsius degrees higher than normally used in that environment.
| Original language | English |
|---|---|
| Pages | 51-63 |
| Number of pages | 13 |
| Volume | 13 |
| No | 8 |
| Specialist publication | Tappi Journal |
| DOIs | |
| State | Published - Aug 1 2014 |
Funding
Dane F. Wilson’s efforts in reviewing this document are recognized and appreciated. Adam Willoughby led the effort to assemble the probes and the data collection system; Tyson Jordan and Hu Longmire carried out the metallographic sample preparation and light microscopy examinations; Tracie Lowe conducted the scanning electron microscope examinations; Robbie Meisner performed the X-ray diffraction and Maggie Connatser the Raman examinations of the deposits. Employees of all four of the facilities where probes were exposed assisted with installation and removal of the probes, as well as helped in troubleshooting several problems that arose. In particular, the help provided by Curtis Clemmons at Covington, Bob Erickson at Crofton, Billy Zemo at Gadsden, and Peter Hildering at Port Mellon is appreciated. Neville Stead of FPInnovations provided considerable help in installation, maintenance, and removal of the Crofton and Port Mellon corrosion probes. Material for the corrosion samples was provided by Haynes International, Rolled Alloys, Thys-senKrupp VDM, and Sandvik Materials Technology, and other in-kind contributions were provided by Åbo Akademi University, Andritz Oy, Babcock & Wilcox, Catalyst Paper, Chalmers University of Technology, Domtar Corp., FM Global, FPInnovations, Foster Wheeler, Georgia Institute of Technology, Howe Sound Pulp & Paper, International Paper, Mead-Westvaco, Metso Power, Outokumpu Stainless, SharpConsultant, Southern Company, Special Metals, University of Toronto Pulp and Paper Centre, Vattenfall Power, and the Weyerhaeuser Co. Research was sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under contract DE-AC05-00OR22725 with UT-Battelle LLC.
| Funders | Funder number |
|---|---|
| UT-Battelle LLC | |
| U.S. Department of Energy | |
| Advanced Manufacturing Office | DE-AC05-00OR22725 |
| Office of Energy Efficiency and Renewable Energy |
